require 'rmagick'

imgl = Magick::ImageList.new
imgl.new_image(500, 300, Magick::HatchFill.new('white', 'lightcyan2'))

gc = Magick::Draw.new

# Draw path with quadratic bezier commands
gc.fill_opacity 0
gc.stroke 'red'
gc.stroke_width 3
gc.path 'M20,150 Q120,25 220,150 T420,150'

# Annotate
# Show end points
gc.fill_opacity 1
gc.stroke 'grey50'
gc.stroke_width 1
gc.circle 20, 150,   23, 153
gc.circle 220, 150, 223, 153
gc.circle 420, 150, 423, 153

# Show control points
gc.fill 'black'
gc.stroke 'transparent'
gc.circle 120, 25,  123, 28
gc.circle 320, 275, 323, 278

# Show connector lines
gc.line  20, 150, 120, 25
gc.line 120, 25,  320, 275
gc.line 320, 275, 420, 150

# Add labels
gc.font_weight Magick::NormalWeight
gc.font_style Magick::NormalStyle

# Add end point labels
gc.text  30, 155, "'20,150'"
gc.text 230, 155, "'220,150'"
gc.text 430, 155, "'420,150'"

# Add control point labels
gc.text 130, 30, "'120,25'"
gc.text 330, 280, "'320,275'"

gc.draw imgl

imgl.border!(1, 1, 'lightcyan2')
# imgl.display
imgl.write 'qbezierpath.gif'
